Linear actuator and manufacturing method

Abstract

A linear actuator includes a roller screw nut, a roller screw shaft and a plurality of planetary rollers forming an inverted roller screw mechanism. A bearing supports a rotating part of the linear actuator. The bearing includes a mounting member and a plurality of bearing rollers engaging a first bearing portion of the mounting member and a second bearing portion of the rotating part. The plurality of bearing rollers is axially fixed relative to the rotating part and the mounting member. A manufacturing method for the linear actuator is also provided.

The invention claimed is: 
     
       1. A linear actuator, comprising:
 a roller screw nut, a roller screw shaft and a plurality of planetary rollers forming an inverted roller screw mechanism, said roller screw nut or said roller screw shaft forming a rotating part of the linear actuator; and 
 a bearing supporting said rotating part, said bearing including a mounting member and a plurality of grooved bearing rollers, said mounting member having a first bearing portion; 
 said plurality of grooved bearing rollers engaging said first bearing portion and a second bearing portion of said rotating part, and said plurality of grooved bearing rollers being axially fixed relative to said rotating part and said mounting member. 
 
     
     
       2. The linear actuator according to  claim 1 , wherein said mounting member has a first threading, said rotating part has a second threading, and each bearing roller of said plurality of grooved bearing rollers includes at least one groove forming a threading meshing with said first threading and said second threading. 
     
     
       3. The linear actuator according to  claim 2 , wherein said threadings of said bearing rollers, said first threading and said second threading each have a helix angle being equal. 
     
     
       4. The linear actuator according to  claim 1 , wherein said roller screw nut forms said rotating part and includes said second bearing portion. 
     
     
       5. The linear actuator according to  claim 2 , wherein said roller screw nut has a third threading meshing with said plurality of planetary rollers, and said second bearing portion at least partially overlaps axially with said third threading. 
     
     
       6. The linear actuator according to  claim 1 , wherein said roller screw shaft forms said rotating part and includes said second bearing portion. 
     
     
       7. The linear actuator according to  claim 1 , wherein said mounting member is at least partially hollow, said mounting member has an inner surface, and said first bearing portion is disposed on said inner surface of said mounting member. 
     
     
       8. The linear actuator according to  claim 1 , wherein said rotating part has a circumferential outer surface, and said second bearing portion is disposed on said circumferential outer surface. 
     
     
       9. The linear actuator according to  claim 1 , wherein said roller screw nut has an inner surface, and said second bearing portion is disposed on said inner surface. 
     
     
       10. The linear actuator according to  claim 1 , wherein said rotating part has a threading meshing with said plurality of planetary rollers, and said second bearing portion is disposed axially adjacent said threading. 
     
     
       11. The linear actuator according to  claim 1 , wherein at least a part of said mounting member axially extends into said roller screw nut. 
     
     
       12. The linear actuator according to  claim 9 , wherein at least a part of said mounting member axially extends into said roller screw nut. 
     
     
       13. The linear actuator according to  claim 1 , wherein said mounting member has a circumferential outer surface disposed inside said roller screw nut, and said first bearing portion is disposed on said circumferential outer surface of said mounting member. 
     
     
       14. The linear actuator according to  claim 9 , wherein said mounting member has a circumferential outer surface disposed inside said roller screw nut, and said first bearing portion is disposed on said circumferential outer surface of said mounting member. 
     
     
       15. The linear actuator according to  claim 1 , wherein said rotating part includes a collar, and said second bearing portion is disposed on said collar. 
     
     
       16. The linear actuator according to  claim 1 , wherein each bearing roller of said plurality of grooved bearing rollers has grooves forming respective closed loops separated by a plurality of ridges, said mounting member and said rotating part each have a plurality of complementary grooves, and said plurality of ridges mesh with said plurality of complementary grooves of said mounting member and said rotating part. 
     
     
       17. A method for manufacturing a linear actuator, the method comprising:
 providing the linear actuator according to  claim 1  by carrying out a single process step for creating a threading of said rotating part for meshing with said plurality of planetary rollers and for creating said second portion of said rotating part for engagement by said plurality of grooved bearing rollers.